The present invention relates generally to connections or hitches between a tow vehicle such as a pick-up truck and a trailer, and more specifically to a force absorber for such connections, especially suitable for fifth wheels.
Prior hitches between pick-up trucks commercially marketed are rigid in that they do not absorb forces between the two vehicle and the trailer, but instead transmit such forces. The result can lead to driver fatigue, and over an extended period, premature mechanical failure in the truck. Such commercial hitches have a pair of mounts above the wheel wells with a readily removable cross bar running between them with the hitch in the center of the cross bar.
The present invention provides force absorbing, resulting in a much smoother ride. However, in force absorbers of this kind, serious binding problems may occur in the mechanism. The binding can eliminate or at least substantially reduce the effectiveness of the force absorbing characteristics, rendering the device unsatisfactory.
Several patents show force absorbing mechanisms using various spring arrangements or elastomerics for use between tow vehicles and trailers. However, the binding problem has not been addressed as in the present invention. Furthermore, such systems apparently fail to have a force absorbing mechanism in combination with a readily removable cross bar in a pick-up truck for use with a fifth wheel hitched in the center of the bar according to the present invention.
U.S. Pat. No. 1,136,176 shows a double spring configuration suitable for a tractor. U.S. Pat. No. 2,093,761 shows a fifth wheel hitch with springs mounted to a truck chassis. U.S. Pat. No. 3,904,226, 4,027,893 show force absorbing hitches on rear bumpers of pick-up trucks. Other systems are disclosed in U.S. Pat. Nos. 1,288,425, 1,396,500, 2,196,537, 2,783,039, and 3,297,340. None of these teach the present invention. The present invention may include a mechanism to allow pivoting such as a tapered portion between a slide body and a shaft to reduce binding. Furthermore, material such as bronze may be used next to steel to reduce binding and galling. The present invention provides the convenience of a ready-removal cross bar to expose the pick-up truck bed while still providing force absorbing with a relatively simple design. Springs under precompression are preferably used to prevent play or unwanted sliding in the slide body. A replaceable bronze wear plate may be used and replaced without needing to replace the entire device. These and other features set forth in more detail below provide a significant advance in the art.